For a liquid crystal display apparatus including a liquid crystal panel that modulates light-source light in accordance with a video signal and a backlight source for applying light to the liquid crystal panel, technologies have been known that improve quality of displayed video by controlling the emission luminance of the backlight source depending on an input video signal.
For example, in some technologies, an average picture level (hereinafter, APL) of one frame is calculated as a feature quantity of an input video signal to adjust the emission luminance of the backlight source in accordance with the APL, or the emission luminance of the backlight source is adjusted based on the maximum luminance level and the minimum luminance level among luminance levels of pixels in one frame of the input video signal, and in other technologies, the emission luminance of the backlight source is adjusted by analyzing histogram, etc., of the luminance levels of the input video signal.
For example, Patent Document 1 discloses a liquid crystal display apparatus for improving a feeling of visual contrast while evading black floating interference, for reproducing glossy and high-quality videos, and for providing videos of screen luminance optimum to a viewer. The liquid crystal display apparatus of patent document 1 detects APL of the input video signal to control the emission luminance of the backlight source in accordance with the detected APL. A peak value of the input video signal is also detected and the control characteristics are corrected in the emission luminance of the backlight source in accordance with the peak value.
Patent Document 2 discloses an image display device capable of improving a feeling of visual contrast without increasing power consumption of a light source by correlating contrast adjustment (signal amplitude control) with light-source emission luminance adjustment to adjust the light-source luminance such that a visually perceived average luminance level is not changed.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-258669    Patent Document 2: Japanese Patent No. 3215400